The use of springs for centering shafts that are co-supported by fluid dampers are well known and, as for example, the spring exemplified in U.S. Pat. No. Re. 30,210 granted to D. F. Buono, N. G. Carlson, D. H. Hibner and D. C. Moringiello on Feb. 12, 1980 and commonly assigned to United Technologies Corporation, the assignee of this patent application, is typical of the prior art. As disclosed in this reissue patent, the spring is mounted coaxially with the shaft and extends axially relative to the bearing so that it is fixed at one end and attached to the bearing on its remote end thus forming a cantilever support.
U.S. Pat. No. 4,213,661 granted to R. A. Marmol (co-inventor of the invention presented in this patent application) on July 22, 1980 and likewise commonly assigned to United Technologies Corporation, discloses another type of bearing support that has heretofore incorporated a spring that circumscribes the bearing and is comprised of several arcuate segments each of which defines fluid chambers for effectuating film squeeze damping. One of the segments of this type of spring is disclosed in FIG. 1 (prior art) to illustrate the complexity thereof and differentiate it relative to the present invention. As noted, the outer surface is grooved to form an ellipse to accept an "O" seal. Fluid is introduced adjacent the surface bounded by the "O" seal. The surfaces of the segment, the inner surface and outer surface, are matched to their respective mating parts necessitating machining each surface to different center lines. Obviously, to assure minimal leakage, the tolerances must be extremely low necessitating lap fittings. In addition, each segment must be individually fed with supply oil. Obviously, the cost of fabricating these types of supports is significant.
The present invention occupies a shorter axial envelope and avoids the disadvantages of the arcuate segmented load supports enumerated in the above. We have found that we can provide a spring support for a bearing by disposing a pair of arcuate segments on either side of, or a single set of arcuate segments surrounding, the bearing, thus permitting the use of an annular fluid chamber that is continuously fed with supply oil. The spring contemplated by this invention absorbs as high a load imbalance as that capable of being absorbed by the support structure exemplified in the prior art.